Final answer:
The Baldachin over the high-altar of St. Peter's Basilica is a work attributed to Gian Lorenzo Bernini, not any of the other architects listed in the options provided.
Step-by-step explanation:
The Baldachin over the high-altar of St. Peter's Basilica is attributed to the renowned artist and architect Gian Lorenzo Bernini. Constructed from 1624 to 1633, the Baldachin (sometimes spelled Baldacchino) is a masterful work that stands 28.74 meters high and is made of bronze, forming a free-standing space around the altar beneath the dome of the basilica. None of the other figures mentioned in the options, A) Imhotep, B) Senenmut, C) Kallikrates, or D) Iktinos, are associated with this work; these individuals are linked to other significant historical architectural achievements, such as the design of the Parthenon in Athens and the Step Pyramid at Saqqara.
Bernini's Baldachin is an impressive Baroque piece designed to create a connection between the massive scale of the basilica and the human experience. It is an emblematic example of Bernini's contribution to the Baroque period, reflecting his ability to tell stories in stone, as seen in the detailed sculptures that adorn the canopy.